The UK budget deficit will swell this year to overtake Greece, becoming the worst in the European Union, the European commission said today in a stark warning on the eve of the election.

The commission’s spring economic forecasts put the UK deficit for this calendar year at 12% of GDP, the highest of all 27 EU nations and worse than the Treasury’s own forecasts.

The country’s budget shortfall was the third largest in the EU last year but will overtake both Greece and Ireland this year, according to the forecasts. Greece’s measures to tackle its public finances problems are seen cutting the deficit there to 9.3% of GDP.

Worries about Britain’s public finances – in their worst state since the end of the second world war – continue to unnerve financial markets and analysts are divided over whether a hung parliament will have the clout to rapidly reduce the deficit.